Essential to normal heart function are four heart valves, which allow blood to pass through the four chambers of the heart in one direction. The valves have either two or three cusps, flaps, or leaflets, which comprise fibrous tissue that attaches to the walls of the heart. The cusps open when the blood flow is flowing correctly and then close to form a tight seal to prevent backflow.
The four chambers are known as the right and left atria (upper chambers) and right and left ventricles (lower chambers). The four valves that control blood flow are known as the tricuspid, mitral, pulmonary, and aortic valves. In a normally functioning heart, the tricuspid valve allows one-way flow of deoxygenated blood from the right upper chamber (right atrium) to the right lower chamber (right ventricle). When the right ventricle contracts, the pulmonary valve allows one-way blood flow from the right ventricle to the pulmonary artery, which carries the deoxygenated blood to the lungs. The mitral valve, also a one-way valve, allows oxygenated blood, which has returned to the left upper chamber (left atrium), to flow to the left lower chamber (left ventricle). When the left ventricle contracts, the oxygenated blood is pumped through the aortic valve to the aorta.
Certain heart abnormalities result from heart valve defects, such as valvular insufficiency. Valvular insufficiency is a common cardiac abnormality where the valve leaflets do not completely close. This allows regurgitation (i.e., backward leakage of blood at a heart valve). Such regurgitation requires the heart to work harder as it must pump both the regular volume of blood and the blood that has regurgitated. If this insufficiency is not corrected, the added workload can eventually result in heart failure.
Another valve defect or disease, which typically occurs in the aortic valve, is stenosis or calcification. This involves calcium buildup in the valve which impedes proper valve leaflet movement.
In the case of aortic valve insufficiency or stenosis, treatment typically involves removal of the leaflets and replacement with a valve prosthesis. However, known procedures have involved generally complicated approaches that can result in the patient being on cardio-pulmonary bypass for an extended period of time. One procedure used in attaching a replacement aortic valve to the aortic annulus involves sewing the replacement aortic valve to the aorta with sutures. This procedure is time consuming and labor intensive. The surgeon individually places between about 15 and 24 stitches into the aortic valve annulus. Often, access to the valve annulus is tenuous, greatly increasing the difficulty of stitch replacement. After the stitches are placed in the annulus, they are then fed through the replacement valve. The valve is “parachuted” down to the annulus. Finally, the surgeon individually ties each suture. Tying sutures in areas of difficult access runs the risk of suture breakage, tying the suture too tight (potentially damaging tissue), or tying the tissue too loose such that the valve is not properly secured to the valve annulus.
Applicants believe that there remains a need for improved aortic valvular repair apparatus and methods that use minimally invasive techniques and/or reduce time in surgery.